Power Synthesizer

Abstract

To reduce the size of a power synthesizer.SOLUTION: A power synthesizer has a first substrate with a first microstrip line, a second substrate with a second microstrip line, and a hollow waveguide with a metallic film on the hollow inner wall that is connected to the first and second microstrip lines and synthesizes and transmits the first power transmitted over the first microstrip line and the second power transmitted over the second microstrip line.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a power combiner. [Background technology]

[0002] For high-density mounting of microstrip lines, a structure is known in which microstrip lines are provided on both sides of a substrate having dielectric layers on both sides of a ground conductor substrate. In this case, it is known that in order to guide electromagnetic waves transmitted through one microstrip line to the other microstrip line, a coupling hole is provided in the ground conductor substrate and a housing is provided to shield the electromagnetic waves radiated from the coupling hole (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-101286 A Summary of the Invention [Problem to be solved by the invention]

[0004] In communication systems such as radar systems and mobile phones, in order to increase the output power, multiple transistors are arranged in parallel and the output power of these multiple transistors is combined by a power combiner. A tournament-type power combiner is known as such a power combiner. However, the tournament-type power combiner itself becomes large.

[0005] One aspect aims to reduce the size of the power combiner. [Means for solving the problem]

[0006] In one embodiment, a first microstrip line is provided. It is a dielectric substrate A first substrate and a second microstrip line are provided. It is a dielectric substratea second substrate; and a hollow waveguide having a metal film provided on a hollow inner wall, the hollow waveguide being connected to the first microstrip line and the second microstrip line, and transmitting a first power transmitted through the first microstrip line and a second power transmitted through the second microstrip line in a combined form. The first substrate has a first opening in front of the first microstrip line, and the second substrate has a second opening in front of the second microstrip line, and the hollow waveguide is formed by stacking the first substrate and the second substrate and connecting the first opening and the second opening. , a power combiner. In one aspect, the power combiner includes a first substrate having a first microstrip line, a second substrate having a second microstrip line, and a hollow waveguide having a metal film on its inner wall, the hollow waveguide being connected to the first microstrip line and the second microstrip line, and combining and transmitting a first power transmitted through the first microstrip line and a second power transmitted through the second microstrip line, the first substrate having a first protrusion portion protruding into the hollow waveguide and having the first microstrip line provided thereon, the second substrate having a second protrusion portion protruding into the hollow waveguide and having the second microstrip line provided thereon, the first substrate and the second substrate being stacked such that the first protrusion portion and the second protrusion portion overlap in the stacking direction, the first power is transmitted to the hollow waveguide via the first protrusion portion, and the second power is transmitted to the hollow waveguide via the second protrusion portion. Effect of the Invention

[0007] One aspect is that the power combiner can be made smaller. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a power combiner according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 3 is an exploded perspective view of the power combiner of FIG. [Figure 4] 4(a) and 4(b) are perspective views of the line substrate. [Diagram 5] 5(a) and 5(b) are perspective views of the line substrate. [Figure 6] 6(a) and 6(b) are perspective views of the intermediate substrate. [Figure 7] FIG. 7 is a cross-sectional view illustrating the operation of the power combiner according to the first embodiment. [Figure 8] 8(a) and 8(b) are plan views showing a power combiner according to a comparative example. [Figure 9] FIG. 9 is a cross-sectional view of the hollow waveguide of FIGS. 8(a) and 8(b). [Figure 10] FIG. 10 is a perspective view of a power combiner according to the second embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken along line AA in FIG. [Figure 12] FIG. 12 is an exploded perspective view of the power combiner of FIG. [Figure 13]13(a) and 13(b) are perspective views of the intermediate substrate. [Figure 14] FIG. 14 is a cross-sectional view illustrating the operation of the power combiner according to the second embodiment. [Figure 15] FIG. 15 is a diagram showing various dimensions used in the simulation. [Figure 16] FIG. 16 illustrates a simulation result of the electric field vector of the power combiner according to the second embodiment. [Figure 17] FIG. 17 illustrates a simulation result of loss characteristics of the power combiner according to the second embodiment. [Figure 18] FIG. 18(a) is a cross-sectional view of a power combiner according to a third embodiment, and FIG. 18(b) is a cross-sectional view showing the operation of the power combiner according to the third embodiment. [Figure 19] FIG. 19 is a cross-sectional view of a power combiner according to the fourth embodiment. [Figure 20] FIG. 20 is a cross-sectional view of a power combiner according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0010] FIG. 1 is a perspective view of a power combiner 100 according to a first embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1. FIG. 3 is an exploded perspective view of the power combiner 100 in FIG. 1. The power combiner 100 combines and transmits output powers of a plurality of transistors connected in parallel, and is used in various systems, such as radar systems and communication systems such as mobile phones. As shown in FIGS. 1 to 3, the power combiner 100 includes a line substrate 10a on which a microstrip line 13a is provided, a line substrate 10b on which a microstrip line 13b is provided, and a hollow waveguide 60. The extension direction of the microstrip lines 13a and 13b is the X-axis direction, the width direction is the Y-axis direction, and the lamination direction of the line substrates 10a and 10b is the Z-axis direction. In the following description, when referring to the up-down direction of the power combiner, the positive direction of the Z-axis direction is the upward direction, and the negative direction is the downward direction.

[0011] The microstrip line 13a is provided on the upper surface of the line substrate 10a, and the lower surface of the line substrate 10a is covered with a metal film 15a. The microstrip line 13b is provided on the lower surface of the line substrate 10b, and the upper surface of the line substrate 10b is covered with a metal film 15b. The metal films 15a and 15b are ground conductor films provided on the surfaces of the line substrates 10a and 10b opposite to the surfaces of the microstrip lines 13a and 13b.

[0012] An intermediate substrate 30 is provided between the line substrate 10a and the line substrate 10b. The upper surface of the intermediate substrate 30 is covered with a metal film 34, and the lower surface is covered with a metal film 35. The metal film 34 contacts a metal film 15a provided on the lower surface of the line substrate 10a, and the metal film 35 contacts a metal film 15b provided on the upper surface of the line substrate 10b.

[0013] Here, the line substrates 10a and 10b and the intermediate substrate 30 will be described in detail. Fig. 4(a) and Fig. 4(b) are perspective views of the line substrate 10a. Fig. 4(a) is a perspective view of the line substrate 10a seen from the +Z side, and Fig. 4(b) is a perspective view of the line substrate 10a seen from the -Z side. As shown in Figs. 4(a) and 4(b), the line substrate 10a has a central portion cut out to form an opening 19a. The line substrate 10a also has a protrusion 18a that protrudes into the opening 19a from the side surface of the opening 19a on the side where the microstrip line 13a is provided.

[0014] As shown in FIG. 4(a), the microstrip line 13a provided on the upper surface 11a of the line substrate 10a extends from the side 20a of the upper surface 11a to the opening 19a. The microstrip line 13a is also provided on the protruding portion 18a. For example, the microstrip line 13a has a constant width (a constant length in the Y-axis direction) from the side 20a to a certain distance, and then the width tapers toward the opening 19a, and the width further increases near the opening 19a. A metal film 14a is provided between the opening 19a and sides 20b and 20c that intersect with the side 20a. The line substrate 10a has two notches 17a on the side of the opening 19a on which the microstrip line 13a is provided. The two notches 17a sandwich the protruding portion 18a. The microstrip line 13a and the metal film 14a are separated by the notch 17a.

[0015] 4(b), the lower surface 12a of the line substrate 10a is covered with a metal film 15a. The metal film 15a is also provided on the protruding portion 18a.

[0016] As shown in Figures 4(a) and 4(b), a metal film 16a is provided on the side surface of the opening 19a of the line substrate 10a, in contact with the metal film 14a and the metal film 15a. No metal film is provided on the side surface between the two notches 17a of the opening 19a of the line substrate 10a. Therefore, no metal film is provided on the side surface of the protrusion 18a.

[0017] 5(a) and 5(b) are perspective views of the line substrate 10b. FIG. 5(a) is a perspective view of the line substrate 10b seen from the +Z side, and FIG. 5(b) is a perspective view of the line substrate 10b seen from the -Z side. The line substrate 10b is formed by turning the line substrate 10a upside down. As shown in FIG. 5(a) and FIG. 5(b), the line substrate 10b has an opening 19b formed by cutting out a central portion, and has a protrusion 18b protruding into the opening 19b from the side of the opening 19b on the side where the microstrip line 13b is provided.

[0018] 5(a), the top surface 11b of the line substrate 10b is covered with a metal film 15b. The metal film 15b is also provided on the protruding portion 18b.

[0019] As shown in FIG. 5(b), the microstrip line 13b provided on the lower surface 12b of the line substrate 10b extends from the side 21a of the lower surface 12b to the opening 19b. The microstrip line 13b is also provided on the protruding portion 18b. For example, the microstrip line 13b has a constant width (a constant length in the Y-axis direction) from the side 21a to a certain distance, and then the width tapers toward the opening 19b, and the width further increases near the opening 19b. A metal film 14b is provided between the opening 19b and the sides 21b and 21c intersecting the side 21a. The line substrate 10b has two notches 17b on the side of the opening 19b on the side where the microstrip line 13b is provided. The two notches 17b sandwich the protruding portion 18b. The microstrip line 13b and the metal film 14b are separated by the notch 17b.

[0020] As shown in Figures 5(a) and 5(b), a metal film 16b is provided on the side surface of an opening 19b of the line substrate 10b, in contact with the metal film 14b and the metal film 15b. No metal film is provided on the side surface between the two notches 17b of the opening 19b of the line substrate 10b. Therefore, no metal film is provided on the side surface of the protrusion 18b.

[0021] 6(a) and 6(b) are perspective views of intermediate substrate 30. FIG. 6(a) is a perspective view of intermediate substrate 30 viewed from the +Z side, and FIG. 6(b) is a perspective view of intermediate substrate 30 viewed from the -Z side. As shown in FIG. 6(a) and FIG. 6(b), intermediate substrate 30 has a central portion cut out to form opening 39. Intermediate substrate 30 also has protrusion 38 on the side surface of opening 39 that protrudes into opening 39. Protrusion 38 is provided at a position corresponding to protrusion 18a of line substrate 10a and protrusion 18b of line substrate 10b.

[0022] As shown in Fig. 6(a), the upper surface 31 of the intermediate substrate 30 is covered with a metal film 34. The metal film 34 is also provided on the protrusions 38. As shown in Fig. 6(b), the lower surface 32 of the intermediate substrate 30 is covered with a metal film 35. The metal film 35 is also provided on the protrusions 38.

[0023] 6(a) and 6(b), a metal film 36 is provided on the side surface of the opening 39 of the intermediate substrate 30, the metal film 36 being in contact with the metal film 34 and the metal film 35. The metal film 36 is also provided on the side surface of the intermediate substrate 30 on which the protrusion 38 is provided. Thus, the metal film 36 is also provided on the side surface of the protrusion 38.

[0024] 1 to 3, line substrate 10b, intermediate substrate 30, and line substrate 10a are stacked in this order in the +Z direction. An upper substrate 40 is provided on the top surface of line substrate 10a, and a lower substrate 50 is provided on the bottom surface of line substrate 10b, sandwiching openings 19a, 39, and 19b of line substrate 10a, intermediate substrate 30, and line substrate 10b, respectively. This forms a hollow 61 consisting of openings 19a, 39, and 19b.

[0025] The line substrate 10a and the line substrate 10b are laminated such that the microstrip line 13a and the microstrip line 13b overlap in the Z-axis direction. The microstrip line 13a and the microstrip line 13b overlap when half or more of their areas overlap, preferably when 80% or more overlap, more preferably when 90% or more overlap, and even more preferably when 95% or more overlap.

[0026] The upper substrate 40 has a metal film 42 on its upper surface and a metal film 44 on its lower surface. The metal film 44 is in contact with the microstrip line 13a and the metal film 14a provided on the upper surface of the line substrate 10a. Note that the metal film 42 may not be provided.

[0027] The lower substrate 50 has a metal film 52 on its upper surface and a metal film 54 on its lower surface. The metal film 52 is in contact with the microstrip line 13b and the metal film 14b provided on the lower surface of the line substrate 10b. The metal film 54 may not be provided.

[0028] The upper inner wall of the hollow 61 is the lower surface of the upper substrate 40 and is covered with a metal film 44. The lower inner wall of the hollow 61 is the upper surface of the lower substrate 50 and is covered with a metal film 52. The inner wall of the hollow 61 is formed by the side surface of the opening 19a of the line substrate 10a, the side surface of the opening 39 of the intermediate substrate 30, and the side surface of the opening 19b of the line substrate 10b. Since the metal films 16a, 36, and 16b are provided on the respective side surfaces, the inner wall of the hollow 61 is covered with a metal film 62 formed by the metal films 16a, 36, and 16b. Therefore, the hollow 61 functions as a hollow waveguide 60 through which electromagnetic waves propagate. The electromagnetic waves propagate within the hollow 61.

[0029] In addition, the hollow waveguide 60 is not limited to having its inner wall covered with the metal film 62, and may have other configurations, such as a through hole provided in the line substrates 10a and 10b and the intermediate substrate 30 instead of the metal film 62.

[0030] The protrusions 18a, 18b, 38 provided on the line substrates 10a and 10b and the intermediate substrate 30 overlap in the Z-axis direction. Here, the protrusions 18a, 18b, 38 overlap when half or more of their areas overlap, preferably 80% or more overlap, more preferably 90% or more overlap, and even more preferably 95% or more overlap. The overlapped protrusions 18a, 18b, 38 are collectively referred to as protrusions 8. The protrusions 8 have the function of smoothly converting the propagation mode of electromagnetic waves between the microstrip lines 13a and 13b and the hollow waveguide 60. In addition, the width of the microstrip lines 13a and 13b is widened near the openings 19a and 19b, so that the conversion of electromagnetic waves between the microstrip lines 13a and 13b and the hollow waveguide 60 is performed with low loss. Even if the intermediate substrate 30 does not have the protrusions 38, electromagnetic waves can be converted with low loss between the microstrip lines 13a and 13b and the hollow waveguide 60. However, to further reduce loss, it is preferable that the intermediate substrate 30 also has the protrusions 38.

[0031] The line substrates 10a and 10b, the intermediate substrate 30, the upper substrate 40, and the lower substrate 50 are dielectric substrates and are made of, for example, a resin material (such as a fluororesin material). The microstrip lines 13a and 13b, the metal films 14a and 14b, the metal films 15a and 15b, the metal films 16a and 16b, the metal films 34 to 36, the metal films 42 and 44, and the metal films 52 and 54 are made of, for example, a conductive metal such as copper.

[0032] Next, the operation of the power combiner 100 of the first embodiment will be described with reference to Fig. 7. In Fig. 7, arrows indicate electric fields generated when electromagnetic waves propagate through the microstrip lines 13a and 13b. High-frequency signals of opposite phases are input to the microstrip lines 13a and 13b from, for example, two transistors 90a and 90b connected in parallel. For example, a high-frequency signal with an initial phase of 0° is input to the microstrip line 13a, and a high-frequency signal with an initial phase of 180° is input to the microstrip line 13b.

[0033] An electric field is generated when electromagnetic waves propagate through the microstrip lines 13a and 13b. Here, the microstrip line 13a is provided on the upper surface of the line substrate 10a, and the microstrip line 13b is provided on the lower surface of the line substrate 10b. In this case, by inputting high-frequency signals of opposite phases to the microstrip lines 13a and 13b, the electromagnetic waves propagate through the microstrip lines 13a and 13b with the electric field directions being almost the same.

[0034] The electromagnetic waves propagating through the microstrip lines 13a and 13b have their propagation modes converted by the protrusions 8, and then the electric powers of the electromagnetic waves are combined in a state in which the electric field directions are substantially aligned in the hollow waveguide 60. This allows the powers to be combined while suppressing loss reduction.

[0035] [Comparative Example] 8(a) and 8(b) are plan views showing a power combiner according to a comparative example. FIG. 9 is a cross-sectional view of the hollow waveguide 520 of FIG. 8(a) and FIG. 8(b). The power combiner 1000a of Comparative Example 1 shown in FIG. 8(a) is a one-stage tournament type power combiner, and the power combiner 1000b of Comparative Example 2 shown in FIG. 8(b) is a two-stage tournament type power combiner. In the power combiners 1000a and 1000b, a tournament type circuit is formed by the hollow waveguide 520. As shown in FIG. 9, the hollow waveguide 520 is formed by sandwiching the substrate 510 on which the metal film 526 is provided between the substrate 512 on which the metal film 522 is provided and the substrate 514 on which the metal film 524 is provided. An opening is formed in the substrate 510, and the metal film 526 is provided on the side of the opening. The hollow space surrounded by metal film 522 , metal film 524 , and metal film 526 becomes hollow waveguide 520 .

[0036] The power combiner 1000a of the comparative example 1 combines the power of high frequency signals output from two transistors 590a and 590b connected in parallel using a tournament circuit and outputs the result. The power combiner 1000b of the comparative example 2 combines the power of high frequency signals output from four transistors 590a to 590d connected in parallel using a tournament circuit and outputs the result.

[0037] The width W of the hollow waveguide 520 is about 1 / 2 the wavelength of the propagating electromagnetic wave. In the power combiners 1000a and 1000b in which such hollow waveguides 520 are arranged in a tournament configuration, the combiner itself becomes large. This results in a long hollow waveguide 520, which leads to an increase in loss.

[0038] On the other hand, in the power combiner 100 of the first embodiment, as shown in Fig. 1 to Fig. 3, a hollow waveguide 60 is connected to the microstrip line 13a and the microstrip line 13b. The power transmitted through the microstrip line 13a and the power transmitted through the microstrip line 13b are combined and transmitted by the hollow waveguide 60. According to this configuration, the size of the power combiner 100 in the width direction (Y-axis direction) can be set to approximately the width of one hollow waveguide 60, and the power combiner 100 can be made compact. By making the power combiner 100 compact, the length of the hollow waveguide 60 is shortened, and an increase in loss can be suppressed.

[0039] 1 to 3, the hollow waveguide 60 is formed by the openings 19a, 39, and 19b provided in the stacked line substrates 10a, intermediate substrate 30, and line substrate 10b. With this configuration, the size of the power combiner 100 in the width direction (Y-axis direction) is approximately the width of the hollow waveguide 60, and the size of the power combiner 100 in the height direction (Z-axis direction) is approximately the total thickness of the multiple substrates, so that the power combiner 100 can be made compact.

[0040] 2 and 3, the line substrate 10a and the line substrate 10b are laminated such that the microstrip line 13a and the microstrip line 13b overlap in the Z-axis direction (lamination direction). With this configuration, the power transmitted through the microstrip line 13a and the power transmitted through the microstrip line 13b are combined in the hollow waveguide 60 while substantially matching each other in the Z-axis direction, so that the powers can be combined while suppressing loss reduction.

[0041] In the first embodiment, the microstrip line 13a is provided on the upper surface 11a of the line substrate 10a opposite to the line substrate 10b, and the microstrip line 13b is provided on the lower surface 12b of the line substrate 10b opposite to the line substrate 10a. With this configuration, when high frequency signals of opposite phases are input to the microstrip lines 13a and 13b, the powers of the electromagnetic waves are combined in a state in which the directions of the electric fields are substantially aligned in the hollow waveguide 60. Therefore, a power combiner 100 that is compatible with the input of high frequency signals of opposite phases can be obtained.

[0042] In the first embodiment, the power transmitted through the microstrip line 13a is transmitted to the hollow waveguide 60 via the protrusion 18a provided on the line substrate 10a. The power transmitted through the microstrip line 13b is transmitted to the hollow waveguide 60 via the protrusion 18b provided on the line substrate 10b. The protrusions 18a and 18b have a function of smoothly converting the propagation mode of the electromagnetic waves between the microstrip lines 13a and 13b and the hollow waveguide 60, so that the power can be combined while suppressing the decrease in loss. In addition, the line substrates 10a and 10b are stacked such that the protrusions 18a and 18b overlap in the Z-axis direction (stacking direction). As a result, the power transmitted through the microstrip line 13a and the power transmitted through the microstrip line 13b are combined at positions that are approximately the same in the Z-axis direction in the hollow waveguide 60, so that the power can be combined while further suppressing the decrease in loss. EXAMPLES

[0043] FIG. 10 is a perspective view of a power combiner 200 according to a second embodiment. FIG. 11 is a cross-sectional view taken along the line AA in FIG. 10. FIG. 12 is an exploded perspective view of the power combiner 200 in FIG. 10. As shown in FIGS. 10 to 12, the power combiner 200 according to the second embodiment includes four line substrates 10c, 10d, 10e, and 10f. The line substrates 10c and 10e have the same configuration as the line substrate 10a shown in FIGS. 4(a) and 4(b). That is, the line substrate 10c has an opening 19c and a protrusion 18c between two notches 17c. A microstrip line 13c and a metal film 14c are provided on the upper surface of the line substrate 10c. A metal film 15c is provided on the lower surface of the line substrate 10c. A metal film 16c is provided on the side of the line substrate 10c at the opening 19c. The line substrate 10e has an opening 19e and a protrusion 18e between the two notches 17e. A microstrip line 13e and a metal film 14e are provided on the upper surface of the line substrate 10e. A metal film 15e is provided on the lower surface of the line substrate 10e. A metal film 16e is provided on the side of the line substrate 10e at the opening 19e. The metal films 15c and 15e are ground conductor films provided on the surfaces of the line substrates 10c and 10e opposite to the microstrip lines 13c and 13e.

[0044] The line substrates 10d and 10f have the same configuration as the line substrate 10b shown in Fig. 5(a) and Fig. 5(b). That is, the line substrate 10d has an opening 19d and a protruding portion 18d between two notches 17d. A metal film 15d is provided on the upper surface of the line substrate 10d. A microstrip line 13d and a metal film 14d are provided on the lower surface of the line substrate 10d. A metal film 16d is provided on the side surface of the line substrate 10d at the opening 19d. The line substrate 10f has an opening 19f and a protruding portion 18f between two notches 17f. A metal film 15f is provided on the upper surface of the line substrate 10f. A microstrip line 13f and a metal film 14f are provided on the lower surface of the line substrate 10f. A metal film 16f is provided on the side surface of the line substrate 10f at the opening 19f. The metal films 15d and 15f are ground conductor films provided on the surfaces of the line substrates 10d and 10f opposite to the microstrip lines 13d and 13f.

[0045] An intermediate substrate 30 is provided between line substrate 10c and line substrate 10d, and between line substrate 10e and line substrate 10f. A metal film 34 on the upper surface of intermediate substrate 30 provided between line substrate 10c and line substrate 10d contacts metal film 15c of line substrate 10c, and a metal film 35 on the lower surface contacts metal film 15d of line substrate 10d. A metal film 34 on the upper surface of intermediate substrate 30 provided between line substrate 10e and line substrate 10f contacts metal film 15e of line substrate 10e, and a metal film 35 on the lower surface contacts metal film 15f of line substrate 10f.

[0046] Four layers of intermediate substrates 70 are laminated between the line substrate 10d and the line substrate 10e. FIGS. 13(a) and 13(b) are perspective views of the intermediate substrate 70. FIG. 13(a) is a perspective view of the intermediate substrate 70 as viewed from the +Z side, and FIG. 13(b) is a perspective view of the intermediate substrate 70 as viewed from the -Z side. As shown in FIGS. 13(a) and 13(b), the intermediate substrate 70 has a central portion cut out to form an opening 79. The intermediate substrate 70 also has a protrusion 78 protruding into the opening 79 on a side surface of the intermediate substrate 70 at the opening 79. The protrusion 78 is provided at a position corresponding to the protrusions 18c-18f of the line substrates 10c-10f and the protrusion 38 of the intermediate substrate 30.

[0047] As shown in Fig. 13(a), an upper surface 71 of intermediate substrate 70 is covered with a metal film 74. Metal film 74 is also provided on protrusions 78. As shown in Fig. 13(b), a lower surface 72 of intermediate substrate 70 is covered with a metal film 75. Metal film 75 is also provided on protrusions 78.

[0048] 13(a) and 13(b), a metal film 76 is provided on the side surface of intermediate substrate 70 at opening 79, in contact with metal film 74 and metal film 75. Metal film 76 is also provided on the side surface of intermediate substrate 70 on which protrusion 78 is provided. Thus, metal film 76 is also provided on the side surface of protrusion 78. In this manner, intermediate substrate 70 has a similar configuration to intermediate substrate 30, except for the different external shape.

[0049] 10 to 12, line substrate 10f, intermediate substrate 30, line substrate 10e, four-layer intermediate substrate 70, line substrate 10d, intermediate substrate 30, and line substrate 10c are stacked in this order in the +Z direction. An upper substrate 40 is provided on the top surface of line substrate 10c, and a lower substrate 50 is provided on the bottom surface of line substrate 10f, sandwiching openings 19f, 39, 19e, 79, 19d, 39, and 19c, respectively. This forms hollow 61a consisting of openings 19c, 39, 19d, 79, 19e, 39, and 19f.

[0050] The upper inner wall of the hollow 61a is the lower surface of the upper substrate 40 and is covered with the metal film 44. The lower inner wall of the hollow 61a is the upper surface of the lower substrate 50 and is covered with the metal film 52. The inner wall of the hollow 61a is formed by the side surfaces of the line substrates 10c-10f at the openings 19c-19f, the side surface of the intermediate substrate 30 at the opening 39, and the side surface of the intermediate substrate 70 at the opening 79. Since the metal films 16c-16f, 36, and 76 are provided on the respective side surfaces, the inner wall of the hollow 61a is covered with the metal film 62a formed by the metal films 16c-16f, 36, and 76. Therefore, the hollow 61a functions as a hollow waveguide 60a.

[0051] The line substrates 10c-10f are laminated such that the microstrip lines 13c-13f overlap in the Z-axis direction. The protrusions 18c-18f, 38, and 78 provided on the line substrates 10c-10f, the intermediate substrate 30, and the intermediate substrate 70 overlap in the Z-axis direction. The overlapping protrusions 18c-18f, 38, and 78 are collectively referred to as protrusions 8a. The protrusions 8a have the function of smoothly converting the propagation mode of the electromagnetic waves between the microstrip lines 13c-13f and the hollow waveguide 60a. Even if the protrusions 38 and 78 are not provided on the intermediate substrates 30 and 70, the electromagnetic waves can be converted between the microstrip lines 13c-13f and the hollow waveguide 60a with low loss. However, in order to further reduce loss, it is preferable that the protrusions 38 and 78 are also provided on the intermediate substrates 30 and 70.

[0052] Next, the operation of the power combiner 200 of the second embodiment will be described with reference to FIG. 14. In FIG. 14, the arrows indicate electric fields generated when electromagnetic waves propagate through the microstrip lines 13c to 13f. For example, in-phase high-frequency signals are input to the microstrip lines 13c and 13e from two transistors 90a and 90c among the four transistors 90a to 90d connected in parallel. High-frequency signals having a phase opposite to that of the high-frequency signals input to the microstrip lines 13c and 13e are input to the microstrip lines 13d and 13f from the remaining two transistors 90b and 90d. For example, a high-frequency signal having an initial phase of 0° is input to the microstrip lines 13c and 13e, and a high-frequency signal having an initial phase of 180° is input to the microstrip lines 13d and 13f.

[0053] The microstrip lines 13c and 13e are provided on the upper surfaces of the line substrates 10c and 10e, and the microstrip lines 13d and 13f are provided on the lower surfaces of the line substrates 10d and 10f. In this case, an in-phase high-frequency signal is input to the microstrip lines 13c and 13e, and an opposite-phase high-frequency signal to that of the microstrip lines 13c and 13e is input to the microstrip lines 13d and 13f, so that the electromagnetic waves propagating through the microstrip lines 13c to 13f propagate with the electric field directions almost aligned.

[0054] The electromagnetic waves propagating through the microstrip lines 13c to 13f have their propagation modes converted by the protrusions 8a, and then the electric powers of the electromagnetic waves are combined in the hollow waveguide 60a with the electric field directions being substantially aligned, thereby enabling the powers to be combined while suppressing loss reduction.

[0055] [simulation] A simulation performed on the power combiner 200 of the second embodiment will be described. FIG. 15 is a diagram showing various dimensions used in the simulation. In FIG. 15, the microstrip lines 13c to 13f are illustrated as the microstrip lines 13, the metal films 14c to 14f are illustrated as the metal films 14, and the notches 17c to 17f are illustrated as the notches 17. The protrusions 18c to 18f, 38, and 78 are illustrated as the protrusions 8a. The conditions under which the simulation was performed are shown below with reference to FIG. 15. Line boards 10c to 10f, intermediate boards 30 and 70: Rogers RO4003C with a thickness of 1.524 mm Microstrip lines 13c-13f: 35 μm thick copper film Metal films 14c-14f, 15c-15f, 16c-16f, 34-36, 74-76: 35 μm thick copper film Width W1 before taper of microstrip lines 13c to 13f: 9 mm Tapered width W2 of microstrip lines 13c to 13f: 11 mm Microstrip line 13c to 13f taper length L1: 8 mm Width W3 between the notches of microstrip lines 13c to 13f: 18 mm Length of protrusions 18c-18f, 38, 78 L2: 7mm Maximum width of protrusion 18c~18f, 38, 78 W4: 3mm Width of notch 17c~17f W5: 0.5mm Width W6 of hollow waveguide 60a: 25 mm Characteristic impedance of microstrip lines 13c to 13f: 25 Ω In addition, in the simulation, it was assumed that an in-phase high-frequency signal was input to the microstrip lines 13c and 13e, and an anti-phase high-frequency signal was input to the microstrip lines 13d and 13f.

[0056] FIG. 16 shows a simulation result of the electric field vector of the power combiner 200 according to the second embodiment. In FIG. 16, the direction of the arrow indicates the direction of the electric field generated when the electromagnetic wave propagates through the microstrip lines 13c to 13f, and the thickness and length of the arrow indicate the magnitude of the electric field. Note that in FIG. 16, the metal films provided on the upper and lower surfaces of the line substrates 10c to 10f and the intermediate substrates 30 and 70 are omitted. As shown in FIG. 16, it was confirmed that the electromagnetic waves propagating through the microstrip lines 13c to 13f provided on the line substrates 10c to 10f propagate with the electric field directions almost aligned. It was also confirmed that the powers of the electromagnetic waves are combined in the hollow waveguide 60a with the electric field directions almost aligned.

[0057] FIG. 17 shows a simulation result of the loss characteristic of the power combiner 200 according to the second embodiment. The horizontal axis of FIG. 17 is frequency [GHz], and the vertical axis is loss [dB]. As shown in FIG. 17, the power passage loss of the power combiner 200 is about 0.25 dB at 10 GHz. In this manner, it was confirmed that the powers of the electromagnetic waves propagating through the microstrip lines 13c to 13f can be combined with low loss. The reason why the powers are combined with low loss is considered to be that, as shown in FIG. 16, the electromagnetic waves propagating through the microstrip lines 13c to 13f are combined in the hollow waveguide 60a with the electric field directions being almost the same.

[0058] According to the second embodiment, the hollow waveguide 60a is connected to the microstrip lines 13c to 13f. The powers transmitted through the microstrip lines 13c to 13f are combined by the hollow waveguide 60a and then transmitted. Therefore, similar to the first embodiment, the power combiner 200 can be made compact.

[0059] The powers combined in the hollow waveguide are not limited to two powers transmitted through two microstrip lines as in Example 2. The powers combined in the hollow waveguide may be a plurality of powers transmitted through a plurality of microstrip lines, such as four powers transmitted through four microstrip lines. EXAMPLES

[0060] FIG. 18(a) is a cross-sectional view of a power combiner 300 according to a third embodiment, and FIG. 18(b) is a cross-sectional view showing the operation of the power combiner 300 according to the third embodiment. As shown in FIG. 18(a), the power combiner 300 according to the third embodiment is configured such that a lower substrate 50, a line substrate 10j, an intermediate substrate 70, a line substrate 10i, an intermediate substrate 70, a line substrate 10h, an intermediate substrate 70, a line substrate 10g, and an upper substrate 40 are laminated in this order toward the +Z direction. The line substrates 10g to 10j have the same configuration as the line substrate 10a shown in FIG. 4(a) and FIG. 4(b). Therefore, the line substrates 10g to 10j are provided with microstrip lines 13g to 13j on their upper surfaces. In addition, a hollow 61b formed by the openings of the line substrates 10g to 10j and the opening of the intermediate substrate 70 functions as a hollow waveguide 60b. The power transmitted through the microstrip lines 13g to 13j is transmitted to the hollow waveguide 60b via the line substrates 10g to 10j and the protrusions 8b provided on the intermediate substrate 70. The other configurations are the same as those in the second embodiment, and therefore will not be described.

[0061] As shown in FIG. 18(b), the microstrip lines 13g to 13j receive in-phase high-frequency signals from, for example, four transistors 90a to 90d connected in parallel. For example, a high-frequency signal with an initial phase of 0° is input to the microstrip lines 13g to 13j. Since the microstrip lines 13g to 13j are provided on the upper surface of the line substrates 10g to 10j, the electromagnetic waves propagating through the microstrip lines 13g to 13j propagate with the electric field directions almost aligned when the in-phase high-frequency signals are input to the microstrip lines 13g to 13j. Therefore, the electric power of each electromagnetic wave is combined in the hollow waveguide 60b with the electric field directions almost aligned. This allows the power to be combined while suppressing a decrease in loss.

[0062] According to the third embodiment, the hollow waveguide 60b is connected to the microstrip lines 13g to 13j. The powers transmitted through the microstrip lines 13g to 13j are combined by the hollow waveguide 60b and then transmitted. Therefore, similar to the first embodiment, the power combiner 300 can be made compact.

[0063] In the third embodiment, the microstrip line 13g is provided on the upper surface of the line substrate 10g opposite to the line substrate 10h, and the microstrip line 13h is provided on the upper surface of the line substrate 10h on the line substrate 10g side. Similarly, the microstrip line 13h is provided on the upper surface of the line substrate 10h opposite to the line substrate 10i, and the microstrip line 13i is provided on the upper surface of the line substrate 10i on the line substrate 10h side. The microstrip line 13i is provided on the upper surface of the line substrate 10i opposite to the line substrate 10j, and the microstrip line 13j is provided on the upper surface of the line substrate 10j on the line substrate 10i side. According to this configuration, when in-phase high-frequency signals are input to the microstrip lines 13g to 13j, the powers of the electromagnetic waves are combined in a state in which the directions of the electric fields are almost the same in the hollow waveguide 60b. Therefore, a power combiner 300 that is compatible with the case in which in-phase high-frequency signals are input can be obtained. EXAMPLES

[0064] In the first to third embodiments, the inlet side of the hollow waveguide where the high frequency signal is input is described, but in the fourth and fifth embodiments, the outlet side of the hollow waveguide where the high frequency signal is output is described. In the fourth and fifth embodiments, the inlet side is configured as the power combiner 200 in the second embodiment.

[0065] Fig. 19 is a cross-sectional view of a power combiner 400 according to the fourth embodiment. In Fig. 19, the electric field of the electromagnetic wave propagating through the hollow waveguide 60a is indicated by an arrow. As shown in Fig. 19, the power combiner 400 according to the fourth embodiment has a microstrip line 80 and a protrusion 88 provided on a central intermediate substrate 70c among four intermediate substrates 70a to 70d stacked between line substrates 10d and 10e. The microstrip line 80 transmits power transmitted through the hollow waveguide 60a after mode conversion by the protrusion 88.

[0066] The intermediate substrate 70b, the intermediate substrate 70a, the line substrate 10d, the intermediate substrate 30, and the line substrate 10c, which are located on the +Z side of the intermediate substrate 70c and are arranged in the +Z direction in this order, have their +X side ends of the openings shifted to the -X side in the above order. The intermediate substrate 70d, the line substrate 10e, the intermediate substrate 30, and the line substrate 10f, which are located on the -Z side of the intermediate substrate 70c and are arranged in the -Z direction in this order, have their +X side ends of the openings shifted to the -X side in the above order. In addition, the +X side end of the opening of the intermediate substrate 70c is located furthest to the +X side than the other substrates. As a result, the height (length in the Z-axis direction) of the hollow waveguide 60a is stepped down toward the intermediate substrate 70c on which the microstrip line 80 is provided. The other configurations are the same as those of the power combiner according to the second embodiment, and therefore will not be described.

[0067] According to the fourth embodiment, the height of the hollow waveguide 60a gradually decreases toward the intermediate substrate 70c on which the microstrip line 80 to which the power to be transmitted through the hollow waveguide 60a is input is provided. This allows a high-frequency signal to be transmitted through the hollow waveguide 60a to be transmitted to the microstrip line 80 with low loss.

[0068] In the fourth embodiment, the hollow waveguide 60a is stepped down toward the intermediate substrate 70c. By stepping down the height of the hollow waveguide 60a, a structure in which the height of the hollow waveguide 60a gradually decreases can be easily obtained. For example, the stepped steps of the hollow waveguide 60a can be formed by a plurality of line substrates 10c to 10f and intermediate substrates 30, 70a to 70d. EXAMPLES

[0069] Fig. 20 is a cross-sectional view of a power combiner 500 according to the fifth embodiment. In Fig. 20, the electric field of the electromagnetic wave propagating through the hollow waveguide 60a is indicated by arrows. As shown in Fig. 20, in the power combiner 500 of the fifth embodiment, a microstrip line 80 and a protrusion 88 are provided on a central intermediate substrate 70c among four intermediate substrates 70a to 70d stacked between line substrates 10d and 10e, similarly to the power combiner 400 of the fourth embodiment.

[0070] The ends of the openings on the +X side of the line substrates 10c to 10f and the intermediate substrates 30 and 70a to 70d are substantially aligned. In the hollow 61a formed by this opening, a metal member 89a having an inclined surface inclined from the upper substrate 40 toward the intermediate substrate 70c, and a metal member 89b having an inclined surface inclined from the lower substrate 50 toward the intermediate substrate 70c are provided. The metal members 89a and 89b are, for example, blocks made of copper. By providing the metal members 89a and 89b, the height (length in the Z-axis direction) of the hollow waveguide 60a is tapered toward the intermediate substrate 70c on which the microstrip line 80 is provided. The other configurations are the same as those of the power combiner according to the second embodiment, and therefore will not be described.

[0071] According to the fifth embodiment, similarly to the fourth embodiment, the height of the hollow waveguide 60a gradually decreases toward the intermediate substrate 70c on which the microstrip line 80 to which the power to be transmitted through the hollow waveguide 60a is input is provided. Therefore, the high frequency signal transmitted through the hollow waveguide 60a can be transmitted to the microstrip line 80 with low loss.

[0072] In addition, in the fifth embodiment, the hollow waveguide 60a is tapered toward the intermediate substrate 70c. By tapering the height of the hollow waveguide 60a toward the intermediate substrate 70c, a high-frequency signal transmitted through the hollow waveguide 60a can be transmitted to the microstrip line 80 with even lower loss.

[0073] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

[0074] In addition, the following supplementary notes are provided in relation to the above description. (Supplementary Note 1) A power combiner comprising: a first substrate on which a first microstrip line is provided; a second substrate on which a second microstrip line is provided; and a hollow waveguide having a metal film provided on a hollow inner wall, the hollow waveguide being connected to the first microstrip line and the second microstrip line, and combining and transmitting a first power transmitted through the first microstrip line and a second power transmitted through the second microstrip line. (Supplementary Note 2) The power combiner according to Supplementary Note 1, wherein the hollow waveguide is formed by openings provided in a plurality of substrates including the first substrate and the second substrate which are stacked together. (Supplementary Note 3) The power combiner according to Supplementary Note 1 or 2, wherein the first substrate and the second substrate are laminated such that the first microstrip line and the second microstrip line overlap in a lamination direction. (Appendix 4) The power combiner according to any one of appendices 1 to 3, wherein the first substrate and the second substrate are stacked, the first microstrip line is provided on a surface of the first substrate opposite the second substrate, and the second microstrip line is provided on a surface of the second substrate opposite the first substrate. (Supplementary Note 5) The power combiner according to Supplementary Note 4, further comprising a third substrate provided between the first substrate and the second substrate, the third substrate having a first metal film overlapping the first microstrip line on its surface facing the first substrate, and a second metal film overlapping the second microstrip line on its surface facing the second substrate. (Appendix 6) The power combiner according to any one of appendices 1 to 3, wherein the first substrate and the second substrate are stacked, the first microstrip line is provided on a surface of the first substrate opposite the second substrate, and the second microstrip line is provided on a surface of the second substrate facing the first substrate. (Supplementary Note 7) The power combiner according to Supplementary Note 6, wherein a gap is provided between the first substrate and the second substrate, through which the second microstrip line is exposed. (Supplementary Note 8) The power combiner according to any one of Supplementary Notes 1 to 7, wherein the first substrate includes a first protrusion protruding into the hollow waveguide and having the first microstrip line provided thereon, the second substrate includes a second protrusion protruding into the hollow waveguide and having the second microstrip line provided thereon, the first substrate and the second substrate are stacked such that the first protrusion and the second protrusion overlap in a stacking direction, and the first power is transmitted to the hollow waveguide via the first protrusion and the second power is transmitted to the hollow waveguide via the second protrusion. (Supplementary Note 9) A power combiner as described in any one of Supplementary Notes 1 to 8, further comprising a third substrate provided with a third microstrip line to which power to be transmitted through the hollow waveguide is input, the hollow waveguide gradually decreasing in height toward the third substrate. (Supplementary Note 10) The power combiner according to Supplementary Note 9, wherein the hollow waveguide has a height that decreases stepwise toward the third substrate. (Supplementary Note 11) The power combiner according to Supplementary Note 10, wherein the step-like difference is formed by a plurality of substrates including the first substrate and the second substrate stacked together. (Supplementary Note 12) The power combiner according to Supplementary Note 9, wherein the hollow waveguide tapers in height toward the third substrate. (Supplementary Note 13) The power combiner according to Supplementary Note 12, wherein the tapered slope is formed by a metal member provided within the hollow waveguide. [Explanation of symbols]

[0075] 8~8b Protrusion 10a~10j Line board 13~13j Microstrip lines 14~14f Metal film 15a~15j Metal film 16a~16f Metal film 17~17f Cutout 18a~18f Protrusion 19a~19f opening 30 Intermediate board 34, 35, 36 Metal film 38 Protrusion 39 Aperture 40 Upper board 42, 44 Metal film 50 Lower Board 52, 54 Metal film 60, 60a, 60b hollow waveguide 61, 61a, 61b hollow 62, 62a Metal film 70~70d Intermediate board 74, 75, 76 Metal film 78 Protrusion 79 Aperture 80 Microstrip Line 88 Protrusion 89a, 89b Metallic members 100, 200, 300, 400, 500 power combiner

Claims

1. a first substrate which is a dielectric substrate provided with a first microstrip line; a second substrate which is a dielectric substrate on which a second microstrip line is provided; a hollow waveguide having a metal film provided on an inner wall of a hollow waveguide, the hollow waveguide being connected to the first microstrip line and the second microstrip line, and combining and transmitting a first power transmitted through the first microstrip line and a second power transmitted through the second microstrip line, the first substrate has a first opening in front of the first microstrip line; the second substrate has a second opening in front of the second microstrip line; The hollow waveguide is formed by stacking the first substrate and the second substrate and connecting the first opening and the second opening.

2. A first substrate on which a first microstrip line is provided; a second substrate on which a second microstrip line is provided; a hollow waveguide having a metal film provided on an inner wall of a hollow waveguide, the hollow waveguide being connected to the first microstrip line and the second microstrip line, and combining and transmitting a first power transmitted through the first microstrip line and a second power transmitted through the second microstrip line, the first substrate includes a first protrusion portion that protrudes into the hollow waveguide and on which the first microstrip line is provided; the second substrate includes a second protrusion portion that protrudes into the hollow waveguide and on which the second microstrip line is provided; the first substrate and the second substrate are stacked such that the first protrusion and the second protrusion overlap in a stacking direction; The first power is transmitted to the hollow waveguide via the first protrusion, and the second power is transmitted to the hollow waveguide via the second protrusion.

3. 3. The power combiner according to claim 1, wherein the first substrate and the second substrate are laminated such that the first microstrip line and the second microstrip line overlap in a lamination direction.

4. the first microstrip line is provided on a surface of the first substrate opposite to the second substrate, The power combiner according to claim 1 , wherein the second microstrip line is provided on a surface of the second substrate opposite to the first substrate.

5. the first microstrip line is provided on a surface of the first substrate opposite to the second substrate, The power combiner according to claim 1 , wherein the second microstrip line is provided on a surface of the second substrate facing the first substrate.

6. a third substrate provided with a third microstrip line to which power to be transmitted through the hollow waveguide is input; The power combiner of claim 1 , wherein the hollow waveguides taper in height towards the third substrate.

7. The power combiner of claim 6 , wherein the hollow waveguide decreases in height stepwise towards the third substrate.

8. The power combiner of claim 6 , wherein the hollow core waveguides taper in height towards the third substrate.

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